Climate breakdown tipping points

Notice the proviso, providing no tipping points are breached above the words “business as usual” in the infographicwe used in our earlier blogpost: Should the UK food supply be put on a war footing? Yes, and here’s why:

What are these tipping points, and what might their consequences be?

A definition of what a tipping point is
In this useful explainer blogpost, David Armstrong McKay says:

  • Tipping points occur when a change in part of the climate system, the TIPPING ELEMENT becomes
    • self-perpetuating beyond
    • a forcing threshold, leading to
    • substantial and widespread Earth system impacts

David and his colleagues drew up this map of the most significant tipping elements at three sets of temperatures as the Earth heats up:*

 

Global heating will be higher than the 1.5C agreed at the Paris COP. If nothing is done to control carbon emissions, we look set for the 2.7C cited in the first infographic.

That means all the elements marked with a white dot in a red circle looks set to happen.

What gravely concerns scientist is that tipping points have feedback or cascading effects. So passing one threshold can increase the risk of another happening.

To use an apt (sick?) phrase, a 2+C degree rise already ‘baked in’. This dramatically raises the chances of a cascade of tipping points happening, vastly accelerating the pace of climate change.

Chatham House published their 2021 Climate Risk Assessment in time for the greatly disappointing Glasgow COP26 Conference. They had this to say about tipping points:

If cascading tipping points are indeed reached at [these] lower temperatures . . . the severity and frequency of the impacts will be far more extreme, which will turn greatly reduce the capacity of societies the world over to adapt, compounding the impacts.

The melting of the Greenland and Western Antarctic icecaps
Of particular concern are the melting of the icecaps on Greenland (1) and the Western Antarctic (2).

NASA estimates the Greenland icecap melt would lead to a 7.4m rise in sea levels. The Antarctic and Southern Ocean Coalition estimate that the Western Antarctic icecap melt would result in a 60m sea level rise (2)

If /when they melt, how fast would the sea levels rise?
Simply put, no-one knows.  What we do know, however, is:

  • The ice caps have melted before. Cold blooded crocodiles once roamed around the Arctic.
  • The Holocene, the period from about 12,000 years ago to today, has been unusually cool.
    • For most of the Earth’s existence, it’s been much hotter. (3)
    • As you can see from the graph (3), the planet was moving towards another Ice Age, until the fossil-fuelled Industrial Revolution raised CO2 levels in the atmosphere.
  • Sudden temporary cooling could happen (4)  but that would not stop the longer term impact of CO2 emissions. They would also cause much social disruption and suffering, not least because of the impact on agricultural production.
  • The last time the Earth heated up as quickly as it is now was over 6,000 years ago. (5)

The impact on us
The land projected to be below the flood level in 2050 are marked in red on this map:

As we all know, much of the Netherlands is already below sea level. They have excellent sea defences. Likewise, the the UK Government over decades has invested invested in sea defences, in particular to protect London and the low levels around the Humber, York, Lincolnshire and the Ouse Wash.

In this article in Spalding Today, Duncan Browne outlines current sea defence plans in this neck of the woods — much of which is prime agricultural land.

He’s cited a 35cm sea rise by 2050. The prevailing view is that it will be three times this, a metre rise, by 2100.

Yet even this is a conservative estimate. In this substack post, Going under, Bill McGuire says:

The prevailing view, driven by modelling, sees perhaps a metre or so of sea-level rise by the century’s end – enough in its own right to doom low-lying islands and coastlines – but observations argue otherwise. A number of studies suggest that sea levels by 2100 could be two or three metres up on today; perhaps as much as five metres. A truly terrifying scenario. (6)

Fending off a 35cm sea rise is qualitatively different from fending off a few metres sea rise. Two questions for the Government (of the UK, Belgium and the Netherlands):

  • While hoping for the best, what sea defences are they putting in place for the worst?
  • Under either scenario, what are their plans for agricultural production in these areas?
    • And if agri-production is considered non-viable, what plans do they have to produce or access sufficient food from other locations for their populations?

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In the long term . . . When will the British Isles become an archipelago?

Although a runaway scenarios currently appears unlikely with a 2C degree warming, (5) reports of disconcerting events are often in the news. (7)

What is certain, though, when the ice-caps and glaciers do melt, sea levels will rise 70m.

Over what time frame, we simply don’t know. 20 years is highly improbable. 200 or 2000 years? Or more?

It depends on how quickly the ice melts.

After it does happen, the geography of the British Isles would then be an archipelago off a smaller European continent: (8)

No comfort that Birmingham is on land high enough to withstand the deluge.

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(1)  https://sealevel.nasa.gov/news/178/greenlands-rapid-melt-will-mean-more-flooding
see also: https://www.weforum.org/agenda/2022/10/greenland-melting-ice-climate-change-nasa/

(2) https://www.asoc.org/learn/antarctic-ice-and-rising-sea-levels/.
It looks probable that this melt may already be unstoppable: see https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014GL060140

(3) See this explainer from the NOAA: https://www.climate.gov/news-features/climate-qa/whats-hottest-earths-ever-been; also this graph from the article:

(4) e.g. Beyond about 3C degrees, the Atlantic Meridional Overturning Circulation (AMOC) might well flip, thereby changing the weather patterns across the northern hemisphere and affecting ecologies across the world. Or if there were a huge volcanic eruption, such as happened in 1815 with the Mount Tambora, or the 1883 Krakatoa eruptions, there would be temporary coooling — although with huge social disruption and much misery.

(5) This factoid, among many others, was in this informative and useful account of Sea Level Rise by the Smithsonian.

(6) See: https://climatetippingpoints.info/2019/10/14/fact-check-will-2c-of-global-warming-trigger-rapid-runaway-feedbacks/, also by David Armstrong McKay.

(7) See for example, Warming seas are carving into glacier that could trigger sea level rise in the Washington Post on 15 February 2023.

(8) In this scenario, Belgium, the Netherlands and most of Denmark, plus Berlin and Potsdam would be awash too; see https://vividmaps.com/the-world-with-a-70-meters-sea-level-rise/

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*Image reproduced with David’s kind permission: GLOBAÏA for Earth Commission, after Armstrong McKay et al. (2022)

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